This invention relates generally to computer input devices and more particularly to optical detector based interface devices.
It has become increasingly common to computerize systems, from the trivial (e.g., the computerized toaster or coffee pot) to the exceedingly complex (e.g., complicated telecommunications and digital network systems). The advantage of computerization is that such systems become more flexible and powerful. However, the price that must be paid for this power and flexibility is, typically, an increase in the difficulty of the human/machine interface.
The fundamental reason for this problem is that computers operate on principles based on the abstract concepts of mathematics and logic, while humans tend to think in a more spatial manner. People inhabit the real world, and therefore are more comfortable with physical, three-dimensional objects than they are with the abstractions of the computer world. Since people do not think like computers, metaphors are adopted to permit people to effectively communicate with computers. In general, better metaphors permit more satisfying communications between people and computers. There are, of course, a number of human/computer interfaces which allow users, with varying degrees of comfort and ease, to interact with computers. For example, keyboards, computer mice, joysticks, etc. allow users to physically manipulate a three-dimensional object to create an input into a computer system. However, these human/computer interfaces are quite artificial in nature, and tend to require a substantial investment in training to be used efficiently. The artificial metaphors tend to break down and systems such as keyboards and mice tend to have inherently low rates of data input.
A number of interfaces are described in the July, 1993 special issue of Communications of the ACM, in an article entitled "Computer Augmented Environments, Back to the Real World." which is herein incorporated by reference. The computer augmented environments reviewed in the article include immersive environments, where rooms are filled with sensors to control the settings of the room, as researched at New York University (NYU) in New York, N.Y. Another example found in the article is the electronic white boards of Wacom and others where ordinary-looking erasers and markers are used to create an electronic "ink." Wellner describes a "DigitalDesk" that uses video cameras, paper, and a special work station to move between the paper and the electronic worlds. Fitzmaurice proposes a "Chameleon" unit which allows a user to walk up to a bookshelf and press a touch-sensitive LCD strip to hear more about a selected book. Finally, MIT Media Lab has a product known as "Programmable Brick" which lets children program by snapping plastic building blocks together, where each of the building blocks includes an embedded microprocessor.
U.S. Pat. No. 4,873,398 issued to Hubby describes a digitizing tablet which is also a flat panel display. The system enables different scenes to be displayed on the tablet while a stylus which emits light moves across the transparent or translucent display surface. The light from the stylus is sensed and its position is used as input to a computer system. Although the scene projected on the display may change and the stylus may take different forms (such as a wide beam airbrush or fiber optic paint brush), the display surface itself does not change and the system is adapted to receive input only from a stylus which produces light at the designed frequency. The system does not identify the stylus and interpret the input based on the identity. The system responds to radiation at the designed wavelength, from whatever source, and "inks" the display (i.e. causes pixels of the flat panel display to become excited) at the corresponding location. The location of a stylus or pen provides input as it moves in contact with the surface of the tablet.
U.S. Pat. No. 4,843,568 issued to Krueger et. al. describes a system which observes a user and provides input based on the user's movement. Krueger et. al. teaches a way to get input directly from the motion of a user without the use of user movable objects as part of the human/computer interface. While strides have been made in attempting to improve human/computer interfaces, there is still progress to be made in this field. Sensor based input systems must somehow extract the intended input data from sensor signals which may include extraneous information caused by the user operating in the field of view of the sensors or other objects observed by the sensors. Dedicated platforms such as the DigitalDesk, the optical display tablet, and the Lego block programming system provide application-specific interfaces which are easy to use, but each platform requires expensive application-specific hardware. In many cases, it may not be economically feasible to provide dedicated hardware with each individual software application. It is also undesirable to require the user to store a piece of hardware per software application. What is needed is a system capable of efficiently filtering meaningful data from noise and a system which can use a single generic hardware interface and yet allow the user to interact with the computer using tangible objects specific to the application being used.